Mr. H. Wedgwood on a System of Geometry, 459 



The blue liquid obtained on shaking copper powder with aqueous 

 ammonia and oxygen or atmospheric air, also contains, besides 

 oxide of copper, nitrite of ammonia ; for if you add some soda to it 

 and boil it to drive off the ammonia and throw down the black 

 oxide of copper, a solution is obtained which, after being evapo- 

 rated to dryness, leaves behind a yellowish salt which consists 

 principally of nitrite of soda. This substance, on being mixed 

 with powdered charcoal and heated, deflagrates, yields with sul- 

 phuric acid strong fumes of nitrous acid, rapidly discharges the 

 colour of indigo solution strongly acidulated by oil of vitriol, and 

 colours brownish a solution of protosulphate of iron containing 

 free sulphuric acid, &c. Common, pure, or atmospheric oxygen, 

 on being put in contact with copper powder and aqueous am- 

 monia, is so rapidly absorbed that I succeeded in depriving com- 

 pletely a whole cubic foot of atmospheric air of its oxygen within 

 a few minutes. Copper and ammonia may therefore be used as 

 eudiometric agents, and for the preparation of nitrogen from com- 

 mon air. The facts above stated appear to me to bear closely upon 

 the important question of nitrification, proving, beyond any doubt, 

 that, under the influence of the contact of some ponderable mat- 

 ters, inactive oxygen is capable, even at the common temperature, 

 of oxidizing both the constituents of ammonia. Before long I 

 hope to be able to give you some more details on nitrification, 

 a chemical phsenomenon which at this present moment deeply 

 engages my attention Yq^j^s most faithfully, 



Basle, Nov. 10, 1856. C. F. ScHONBElN. 



LX. Some Remarks on a System of Geometry derived from an 

 Analysis of our ideas of Direction and Position, By H» 

 Wedgwood, Esq.^ 



THE cardinal definitions on which I find that the whole 

 fabric of demonstration may be made to rest are substan- 

 tially these : — 



A straight line is a line continuing throughout in the same 

 direction. 



Parallel straight lines are lines lying in the same direction 

 from given points in the course of each respectively, though not 

 forming part of the same straight line. 



A plane is a surface passing through every point which can 

 be reached from a given point by motion transverse to a certain 

 constant direction, that is, through every point which can be 

 reached from a given point without motion in a certain constant 

 direction. 



It will be seen that the whole of these definitions depend upon 

 * Communicated by the Author. 

 2H2 



